Method of and apparatus for conjugate grinding of irregularly shaped articles



Nov. 15, 1955 c. E. CLUTTER ET AL 2,723,507

METHOD OF AND APPARATUS FOR CONJUGATE GRINDING OF IRREGULARLY SHAPEDARTICLES Filed April 20, 1953 15 Sheets-Sheet 1 INVENTORS CARL E.CLUTTER THOMAS E. DUGLE y MICHAEL FIELD FRANK M. FOSTER ATT RNEY Nov.15, 1955 Filed April 20, 1953 c. E. CLUTTER ET AL 2,723,507 METHOD OFAND APPARATUS FOR CONJUGATE GRINDING OF IRREGULARLY SHAPED ARTICLES l5Sheets-Sheet 2 INVENTORS CARL E. CLUTTER THOMAS E. DUGLE BY MICHAELFIELD FRANK M. FOSTER MM aw- Nov. 15, 1955 c, cLu -rE ET AL 2,723,507

METHOD OF AND APPARATUS FOR CONJUGATE GRINDING OF IRREGULARLY SHAPEDARTICLES Filed April 20, 1953 15 Sheets-Sheet 5 I I/ ,M W I Q who wow 8m8m b N6 05 wow m mwm R |1l N8 mm 7 NNm 9 3 03 I. l A lllom gm A I l Acom .68 I Now w m8 s m 08 w i 1 .lhl| mwm 8m fi|||i w m N: wwm 5m I iWWN &

IN VEN TORS GLUT CARL E. R THOMAS E. ou E MICHAEL FIELD FRANK M. FOSTER4 1 TTOR 8/ Nov. 15, 1955 c. E. CLUTTER ET AL 2,

METHOD OF AND APPARATUS FOR CONJUGATE GRINDING OF IRREGULARLY SHAPEDARTICLES Filed April 20, 1953 15 Sheets-Sheet 4 INVENTORS CARL E.GLUTTER THOMAS E. DUGLE y MICHAEL FIELD FRANK M. FOSTER Nov. 15. 1955 c.E. CLUTTER ET AL METHOD OF AND APPARATUS FOR CONJUGATE GRINDING OFIRREGULARLY SHAPED ARTICLES 15 Sheets-Sheet 5 Filed April 20, 1953 s mTHE R N L E ETGET V U s N m 1 E ESfl A L N mmm MTMF Filed April 20, 1953Nov. 15, 1955 c, CLUTT ET AL 2,723,507

ND APPARATUS F CONJUGATE. GRINDING OF IRREGULARLY SHAPED ARTICLES 15Sheets-Sheet 6 METHOD OF A 1N! T TORS CARL E. CLU ER THOMAS E. DUGLE yMICHAEL FIE FRANK M. FOST CLUTTER ET AL METHOD OF AND APPARATUS FORCONJUGATE GRINDING 15 Sheets-Sheet 7 Filed April 20, 1953 INVENTORS E,CLUTTER FRANK M. FOSTER I /M M Wow J CARL THOMAS By MICHAEL Nov. 15,1955 c. E. CLUTTER ET AL 2,7

METHOD OF AND APPARATUS FOR CONJUGATE GRINDING OF IRREGULARLY SHAPEDARTICLES Fi Ap l 2 1953 15 Sheets-Sheet 8 IN VEN TORS FRANK M. FOSTERNov. 15, 1955 c. CLUTTER ET AL 2,723,507 I METHOD OF AND APPARATUS FORCONJUGATE GRINDING OF IRREGULARLY SHAPED ARTICLES Filed April 20, 195315 Sheets-Sheet 9 INVENTORS CARL E. CLUTTER THOMAS E. DUGLE BY MICHAELFIELD FRANK M. FOSTER Nov. 15, 1955 c E. CLUTTER ET AL 2,723,507

METHOD OF AND APPARATUS FOR CONJUGATE GRINDING OF IRREGULARLY SHAPEDARTICLES Filed April 20, 1953 15 Sheets-Sheet 10 I TORS #am- 955552 yMICHAEL FIELD FRANK M. FOSTER Nov. 15, 1955 c. E. CLUTTER ET AL2,723,507

FOR CONJUGATE GRINDING HAPED ARTICLES METHOD OF APPARATUS OF EGULARLY S15 Sheets-Sheet 11 Filed April 20, 1953 l7 7 7 NM Q? r 4? w xxx h w s Wxfiw A w Ry fi l 2% 1? Np on 2., w mm mm f m 1\ III w a 9% 7 ww AM J1 1|ilk 2% min [1 w a E m9 wfl T w w o9 mm INVENTORRS L E. GLUTTE MAS E.DUGL HA CAR THO BY MIC EL FIELD FRANK M. FOSTER W 3A TOR Nov. 15, 1955c. E. CLUTTER ET AL 2,

METHOD OF AND APPARATUS FOR CONJUGATE GRINDING OF IRREGULARLY SHAPEDARTICLES Filed April 20, 1953 15 Sheets-$heet l2 INVENTORS CARL E.CLUTTER THOMAS E. DUGLE BY MICHAEL FIELD FRANK M. FOSTER Nov. 15, 1955c. E. CLUTTER ET L METHOD OF AND APPARATUS FOR CONJUGATE GRINDING OFIRREGULARLY SHAPED ARTICLES 15 Sheets-Sheet 13 Filed April 20, 1953 INVEN TORS CARL E. CLUTTER THOMAS E. DUGLE MICHAEL FIELD FRANK M. FOSTERNov. 15. 1955 c. E. CLUTTER ETAL 2,723,507

METHOD OF AND APPARATUS FOR CONJUGATE GRINDING OF IRREGULARLY SHAPEDARTICLES Filed April 20, 1953 15 Sheets-Sheet 14 INVENTORS CARL E.CLUTTER THOMAS E. DUGLE BY MICHAEL FIELD FRANK M. FOSTER Nov. 15, 1955c. E. CLUTTER ET AL 2,723,507

METHOD OF AND APPARATUS FOR CONJUGATE GRINDING 0F IRREGULARLY SHAPEDARTICLES Filed April 20, 1953 15 Sheets-Sheet 15 INVENTORS 532 CARL E.OLUTTER THOMAS E. DUGLE y MICHAEL FIELD g2 FRANK M. FOSTER United StatesPatent METHOD OF AND APPARATUS FOR CONJUGATE glldillglglDlNG OFIRREGULARLY SHAPED ARTI- Carl E. Clutter, Mason, Thomas E. Dugle,

Michael Field, Indian Hill, and Frank M. Foster, Cineinnati, Ohio,assignors, by mesne assignments, to Metcllllit Research Associates,Cincinnati, Ohio, a partner- P Application April 20, 1953, Serial No.349,778 16 Claims. (Cl. 51-143 This invention relates to a method of andapparatus for grinding irregularly shaped articles, such as, by way ofexample, the blades and buckets of gas turbines, by passing an endlessabrasive belt between the said irregularly shaped article and aconjugate form.

An object of the invention is to teach a method of grinding both theconcave and convex surfaces of an irregularly shaped article by means ofan endless abrasive belt passed between the article and a conjugate formwhile the article or the form is being moved along a guided path forsequentially disposing the surface of the form in conjugate coincidencewith portions of the surface of the article.

Another object of the invention is to provide simple yet highlyeffective devices for enabling our method of grinding to be mechanicallyperformed, in lieu of by hand.

A further object of the invention is to provide a device for accuratelygrinding concave surfaces in an article by means of a conjugate formmounted for planetary cyclic motion relative thereto for guiding anabrasive belt over the surface of the article.

Another object of the invention is to provide a device for accuratelygrinding convex surfaces in an article by means of a fixedly mountedconjugate form relative to which the article is moved in a planetarycyclic motion.

Still another object of the invention is to provide grinding deviceshaving the hereinabove described characteristics, with means foraccurately controlling the rate at which the grinding is effected.

Another object of the invention is to provide simple and efiective meansfor automatically equalizing the tension across the face of an endlessabrasive belt after leaving the conjugate form.

These and other objects are attained by the means described herein andas disclosed in the accompanying drawings, in which:

Fig. 1 is a front elevation of a device embodying the teachings of thepresent invention, which is particularly adapted for grinding concavesurfaces on an article.

Fig. 2 is a view, partly in section, taken along line 22 of Fig. 1.

Fig; 3 is a sectional View of the conjugate form supporting means andits actuating mechanism only taken on line 3-3 of Fig. 1.

Fig. 4 is a partial elevational view of the right end of Fig. 3.

Fig. 5 is a top view of Fig. 4.

Fig. 6 is a view of the left end of the conjugate form and spindle onlyof Fig. 3.

Fig. 7 is a sectional view taken on line 7--7 of Fig. 6.

Fig. 8 is a sectional view taken on line 8--8 of Fig. 1.

Fig. 9 is a sectional view taken on line 9-9 of Fig. 8.

Fig. 10 is a sectional view taken on line 10-10 of Fig. 3.

Fig. 11 is a front elevation of a device embodying the teachings of thepresent invention, which is particularly adapted for grinding convexsurfaces on an article.

Cincinnati,

- 2 Fig. 12 is a view, partly in section, taken along line 12-12 of Fig.11.

Fig. 13 is a sectional view taken on line 13-43 of Fig. 1 1.

Fig. 14 is an elevational view of the left end of Fig. 13 with partsthereof being broken away for clarity of detail and understanding.

Fig. 15 is a top view of Fig. 14 with the top cover thereof removed, andwith the control housing in cross section for clarity of detail andunderstanding.

Fig. 16 is a sectional view on line 16-16 of Fig. 15.

Fig. 17 is a sectional 'view of the article supporting cradle and itsactuating mechanism only taken on line 1717 of Fig. 11.

Fig. 18 is an elevational view of the right end of Fig. 17.

Fig. 19 is a sectional view taken on line 19--19 of Fig. 17.

Figs. 20 and 21 are schematic views illustrating the sequential stepsfollowed in grinding the convex surface of the airfoil shape of theblade or bucket for a turbine type engine, Fig. 20 illustrating acompressor blade, Fig. 21 illustrating a turbine bucket.

Fig. 22 is a diagrammatic view of the fluid control system comprising adetail of the present invention.

At the outset it should be noted that the present invention embodiessimple, yet highly efliective means for quickly and accurately grindingto any desired finish concave or convex surfaces on irregularly shapedarticles by guiding an endless abrasive belt over a conjugate form,

and of moving either the article or conjugate form, but

not both, for disposing the surface of the form in conjugate coincidencewith the surface of the article throughout the grinding operation. Weare well aware that the surfaces of irregular articles such as turbineblades and buckets have heretofore been ground to size, by means of anendless abrasive belt which is caused to pass between a conjugate formand that surface of the article to be ground, wherein' both the articleand the conjugate form are simultaneously moved in timed relationship.

In sharp contrast thereto we effect conjugate grinding of the surface ofirregularly shaped articles by passing an endless belt between thearticle to be ground and a conjugate form wherein the article is heldimmovable and stationary in two planes for movement in a third planetoward and away from the conjugate form and wherein the conjugate formis caused to move in a predetermined path relative to the article sothat the surface of the form is coincident with the surface of thearticle at all points of contact throughout the movement of the formabout or relative to the article, in those instances when a concavesurface is being ground. Conversely, when convex surfaces are to beground, the conjugate form is held immovable and stationary in twoplanes for movement in a third plane relative to the article which ismounted for movement along a predetermined path relative to the with thesurface of the article as it is moved about or relative to the form.

For clarity of detail and understanding, we shall first describe onetype of means which has given uniformly excellent results in grindingthe convex surface of irregularly shaped articles.

With particular reference now to Fig. 11, the numeral 30 denotes,generally, a housing which includes a rear wall 32 to which anoscillatable blade cradle is mounted.

With particular reference now to Fig. 17, the numeral 34 denotes aninner cradle and the numeral 36 an outer cradle. The upper end offorward wall 38 of the outer cradle is pivotally journaled to front wallor bearing column 40 as at 42. The upper end of the rear wall 44 of theouter cradle is secured to and carried by spindle other.

46, by meansv of bolts or other suitable retaining means 48.

Spindle 46 is journaled within housing 50 by means of suitableanti-friction elements 52 and 54. A gear 56 is keyed to portion 47 ofthe spindle, said gear engaging rack 58, the reciprocation of said rackbeing utilized to rotate the spindle in opposite directions forimparting an oscillatory motion to outer cradle 36.

The upper end of the forward wallv 60 of the inner cradle is suitablyjournaled as at 62 to the forward wall 38 of the outer cradle at alocation below the pivotal mounting of the front wall of the outercradle to bearing column 40. The rear wall 64 of the inner cradle iskeyed to the forward end of shaft 66, said shaft being journaled inbearings 68'and 70 to the rear wall 44 of the outer cradle.

A planet gear 72 is keyed to that end of shaft 66 remote from the innercradle, said gear being in normal driven relationship with sun gear 74secured to and carried by the forward end of a. stationary shaft 76.Shaft 76 is rigidly and non-rotatably mounted with respect to housing 50by means of clamp plate 78 which, as best illustrated in Fig. 18, may besecured to housing 50 by means of bolts 80. In the preferred embodimentof. the invention clamp plate 78 is provided with means, such as a slit82 and a slot 84 in radial alignment with the clamp plate in order thatsaid plate may be securely though releasably fastened to the free outerend of shaft 76.by means of a bolt 86 which when tightened: will drawthe opposite portions of slot 84 together for clamping; the shaft.

Still referring to Fig. 18, it will be noted that rack 58, hereinafterreferred to as the power rack, is adapted to be reciprocated by means ofa pair of opposed pistons 90 and 92 of cylinders 94 and 96,respectively, which are suitably secured in axial alignment to oppositeends of a block 98 such as, by way of example, tie rods 95, note Figs. 4and 5, which extend through and interconnect end plates 97 and 99,respectively. The rack is mounted to reciprocate within the blockwhich,note Fig. 17, is suitably fastened to wall 100 of housing50.

Fluid media under pressure is alternately introduced into cylinders 94and 96 for driving the rack 58 toward one end or the other of itsstroke, it being noted that the opposite ends of the rack, note Fig. 18,are provided with reduced contact areas 102 against which the outerfaces of pistons 90 and 92 abuttingly engage.

With reference now to Figs. 17 and 18, it will be noted that spur gear104 is rigidly secured to portion 47 of spindle 46, said gear engagingthe teeth of control rack 1.06. A pair of dogs 108 and 110 are securedto and carried by control rack 106 for selectively engaging levers 112and 114, respectively, of reversing valve denoted generally by thenumeral 116, it being understood that this valve controls the flow offluid under pressure, from a suitable source, not illustrated,alternately to either of cylinders 94 or 96. If desired, valve 116 maybe a pilot valve for actuating a-main, master, or control valve for theactuating fluid delivered to cylinders 94 and 96. In Fig; 22 the valve116is shown as a pilot valve for actuating the master reversing valve120 which controls the flow of fluid from pressure line 200 to eitherone or the other of cylinders 96 and 94 for thereby shifting the powerrack from one end of its stroke to the The structural details andoperating cycle of valves 116 and 120 will hereinafter be .more fullydiscussed.

With reference now to Fig. 18, it will be noted that control rack 106will be translated to the left by rotation of gear 104 until such timeas dog 108 contacts lever 112 which will be shifted for changing theflow of fluid from cylinder 94 to cylinder 96, thereby reversing thedirection or travel of power rack 58 to the right, and thereby reversingthe direction of rotation of spindle 46, gear 104 and rack 106.

It. will, be noted that rotation of. spindle 47 will. cause the outercradle 36 to oscillate or rock about an axis extending throughstationary shaft 76 and pivot 42. This oscillation will cause the planetgear 72 of the inner cradle 34 to be driven by sun gear 74which issecured to and carried by stationary shaft 76, for thereby imparting aplanetary motion to the inner. cradle.v It will be noted that the motionthus imparted to inner cradle 34 will be relative to the outer cradle36, said motion being likewise relative to the framework ofthe machine,

Suitable means, such as a mounting, pad 122, are provided on the innercradle for securely though releasably clamping an article, such as, byway of example, a blade having an irregular convex. surface which is tobe ground. The present invention is neither directed to nor concernedwith the particular means utilized for thus securely though releasablyfastening a blade relative to the pad of the inner cradle.

With particular reference now to Fig. 11, the numeral denotes an endlessabrasive belt which passes over idler. pulleys 132, 134, a tensioningpulley 136, drive pulley 138 and over the outer. face 140 of a conjugateform. 141 fixedly mounted relative to and carried by feed arm 142. Drivepulley 138 may be keyed to shaft 144 of an electric motor denotedgenerally by the numeral 146, said motor being utilized to drive theendless belt at a substantially constant lineal speed.

As best illustrated in Figs. 11 and 12, feed arm 142 is securelyfastened to shaft 148, said shaft being rotatably journaled in bearingsand 152 in walls 154 and 156, respectively, of housing 30. Shaft 148 isretated by means of lever 158, the upper end of which is suitablyclamped onto a free end of the shaft, see Fig. 12. The opposite end ofthe lever is pivoted at to a clevis 162 secured to and carried by pistonrod 164 of a cylinder 166 pivotally mounted as at 168 to a mountingbracket 170.

The weight of feed arm 142 is simply and effectively counter-balanced bymeans of spring 172 which surrounds rod 174 pivotally securedto thelower end of lever 158 at 176, and which freely passes through verticalleg 178 of a bracket 180 carried by wall 1180. The free outer end of therod is provided with a stop element 182, spring 1'72 being disposedbetween adjacent faces of leg 178 and element 182, whereby axialmovement of rod 174 to the left will be resiliently resisted by thecounterforce of spring 172.

It will be understood that the application of fluid pressure to cylinder166 will move lever 158 and arm 142 in a clockwise direction about shaft148 for thereby lowering that end of the feed arm remote therefrom.

In the preferred embodiment of the invention the downward motion of thefeed arm 142 is controlled by the operating characteristics of a post210, the upper free end of which isadapted to be contacted by the freelower end of a rest button 212 fixedly secured to and depending fromfeed arm 142. The travel of post 210 is accomplished in two stages, arapid and a slow feed, said rates of feed being controlled by means ofthe post actuating mechanism illustrated in Figs. 13-1 6, inclusive.Post 210 is mounted for free axial movement within bushing 214 mountedin vertical leg of a housing 216. The lower end of post 210 terminatesin an inclined surface 218, and if desired this inclined surface may beincorporated in a shoe suitably secured to' and carried by the post.Axial movement of post 210 is controlled and determined by the relativeposition-of .wedge 220 movable axially in a direction at right angleswith the longitudinal axis of post 210. Axial movement of wedge 220 isaccomplished by means of yoke 224 which is shiftable axially of and in ahorizontal direction along and between laterally spaced walls 226 and228 of a top cover denoted generallyby thenumeral 230,.see. Fig. 14. Anaxially disposed elongated grow e232. having opposed parallel.v sidewalls .234- and 236. and 1a b'ottom wall 238 is provided in lower case240 and between front and rear walls 242 and 244. i

As best illustrated in Fig. 13, a feed wedge 220, a sizing wedge 246 andan intermediate wedge 248 are mounted within elongated groove 232,wherein the feed and sizing wedges are mounted for endwise movement in ahorizontal plane, the intermediate wedge 248 being mounted fortransverse movement in a vertical plane.

A fluid actuated cylinder 250 is provided with its piston in drivenrelationship with yoke 224 via piston rod 252 suitably secured to theend wall of the yoke whereby movement of the piston rod will be impartedto the yoke.

With reference now to Figs. 11 and 13, it should be noted that arm 142will be elevated after each grinding cycle and before the initiation ofa subsequent grinding cycle and that when said arm is in its elevatednonoperative position, rest button 212 will be spaced above and out ofcontact with the uper end of post 210. Post 210 will likewise beelevated to the fully advanced position illustrated in broken outline inFig. 13, it being understood that the feed wedge 220 will be disposed ina fully advanced position to the left for thereby shifting post 210 to afully elevated position.

With reference to Fig. 15, the numeral 254 denotes a control rod one endof which is secured to and carried by yoke 224; the other end of the rodis provided with a camming surface 256 and a free outer end 258. Asuitable limit switch denoted generally by the numeral 260 having acontact arm 262 is mounted adjacent the axial travel of rod 254 wherebycontact element 262 of the switch will be actuated incident to movementof rod 254 to the right.

When contact arm 262 is elevated or engaged by camming face 256 of rod254, switch 260 is utilized to interrupt an electrical circuit tosolenoid 480 of a fluid valve r 476, see Fig. 22, for decreasing therate of flow of actuating fluid from cylinder 250, thereby slowing thelinear movement of feed wedge 220 to the right, resulting in lowering ofpost 210 at a lesser rate.

The lowering cycle of the feed arm142 is as follows:

Initially it will be rapidly lowered from a fully raised or elevatedposition until stop' button 212 engages the free upper end of fullyelevated post 210. As will hereinafter be more fully explained, fluidpressure is applied to cylinder 250 after contact button 212 of the feedram 142 has engaged the upper end of the fully elevated post 210 formaterially decreasing the rate at which the post and feed arm 142 islowered. It should be understood that fluid pressure will becontinuously applied to cylinder 166 during the entire grinding cyclefor exerting a constant lowering force to the feed arm, said force beingopposed by post 210.

With reference again to Fig. 13, it will be noted that the lower surface270 of feed wedge 220 rests upon and slidably engages the upperhorizontal surface 272 of the intermediate wedge 248. The lower surface274 of the wall 238 of the elongate groove 232, and inclined surface 276of the intermediate wedge 248 rests on and slidably engages inclinedsurface 278 of the sizing wedge.

Suitable means are provided for imparting axial movement to the sizingwedge for shifting its lower surface .60 sizing wedge 246 rests upon andslidably engages lower It will be ed by means of a lead screw 284 whichthreadably extgages nut 286 securely though releasably fastened to thewedge by means of retaining plate 288 fastened to the end of the wedgeby means of bolts 290. The lead screw is rotatably journaled in plate292 by bearings 294, said lead screw being thus retained against endwiseaxial movement. Preferably the free outer end of the lead screw isprovided with a socket 296 for the reception of a suitable key, or thelike, by which rotary motion may be imparted to the screw.

In the preferred embodiment of the invention suitable means such as, byway of example, a commercially available counter denoted generally bythe numeral 298, is connected by gears 300, 302 and 304 to gear 306formed integral with lead screw 284, whereby rotation of lead screw 284will actuate the counter mechanism, thereby enabling an operator tolocate the relative position of the s1zmg wedge by noting the indiciaappearing on the counter, it being further noted that the relativehorizontal position of the sizing wedge determines the vertical positionof post 210.

With reference now to Figs. 14, 15 and 16, the numeral 310 denotes asecond lead screw which threadably engages an internally threadednon-symmetrical sleeve 312, the inner end of which terminates in anabutment 314, said sleeve and abutment being mounted for endwisemovement in a complementary channelway 316. A stop 318 secured to andcarried by yoke 224 is adapted to engage abutment 314 for determiningand limiting the maximum forward endwise travel of the yoke and itsassociated feed wedge 220 incident to shifting of the yoke to the left,to its fully advanced position under the influence of a moving forceapplied through cylinder 250. In other words, the relative position ofabutment 314 determines the maximum height of post 210 for any givensetting of the sizing wedge 246.

As in the case of lead screw 284, suitable means are provided inassociation with lead screw 310 for enabling an operator to ascertainand/or pre-set abutment 314 for effecting a desired maximum elevation ofpost 210.

As illustrated in Fig. 15, a third lead screw 320 threadably engages anon-symmetrical sleeve 322 mounted for endwise movement in anon-symmetrical channelway 324. A rod 326 is secured to and carried bysleeve 322, the end of said rod projecting through a suitable opening inend wall 244. Switch 260 is secured to and carried by rod 326, it beingnoted that the relative location of switch 260 and its arm 262 may beshifted to the right or to the left for thereby determining the end ofthe initial or rapid feed of the feed wedge 220.

Su1table indicating means such as a counter-mechanism 298 is associatedwith lead screw 320, as with lead screw 310 and 284, for enabling anoperator to accurately pre-set the relative position of switch 260 forcontrolhng initiation of the slow feed cycle of the feed wedge.

From the foregoing, it will be noted that an operator may, by merelyobserving the indicia appearing at windowspn the variouscounter-mechanism 298 associated with each of the various lead screws284, 310 and 320, accurately determine the limits and relative cyclephases of and through which the post 210 is moved incident to actuationof feed arm 142. A conjugate form 141 having a cam surface 140, which iscoincident with the finished surface to be imparted to the articlemounted on the inner cradle 34 is secured to and fixedly mountedrelative to feed arm 142 by means of a suitable bracket 330 fastened tosaid arm by means of bolts 332. It will be noted that the outer surfaceof conjugate form 141 is so related to the surface of the art cle as toprovide substantial line contact with the article as it is moved by theinner cradle 34 relative to the form 141.

For a more complete understanding of the relationship which occursbetween the conjugate cam surface and the blade, reference is made toFigs. 20 and 21, wherein the numeral 74 denotes the" sun gear and thenumeral 72 the planet gear of Fig. 17. It will be noted that belt 130contactsouter surface 140 of the conjugate form 141 between points A andB, the direction of belt travel over the conjugate form being indicatedby the headed arrow 334, it being understood that the abrasive surfaceof the belt is positioned away from the outer surface of the conjugateform.

The letters C, C1, C2, C3, C4 and C5 illustrate the manner in which anarticle, in this case a blade, secured to and carried by inner cradle 34is presented to the outer surface of the conjugate form incident to therelative motion and oscillation of the inner and outer cradles relativeto the fixed form, it being understood that these relationships areconstant throughout the grinding cycle of a particular blade. It shouldlikewise be understood that the path tirough which the conjugate form141 is moved incident to lowering of the feed arm 142 is alongasubstantially vertical axis during the grinding operation and thatdeviation from straight linear movement of the conjugate form is sominute as to be disregarded for all practical purposes.

With reference now to Fig. 17, it will be noted that the interior ofstationary shaft 76 is hollow as at 340 for providing a passagewaythrough which a quantity of coolant may be introduced via nipple 342threadably engaging the free outer end of shaft 76. A fluid conduit 344is provided in the rear wall 44 of outer cradle 36, said conduit beingin open communication, as at 346, with the interior of shaft 76. A pairof laterally spaced distribution channels 348 (note Fig. 19) areprovided along and interiorly of outer cradle 36, said distributionchannels being in open communication with a plurality of dischargeopenings 350, whereby coolant introduced via hollow shaft 76 will bedischarged upwardly for thoroughly drenching the blade and both sides ofthe endless belt during the grinding process.

Automatic controls In Fig. 22 we have diagrammatically illustrated thevarious fluid controls which are utilized for enabling an operator tomanually initiate a grinding cycle after having mounted an article onthe pad 122 of the inner cradle whereby the convex surface of thearticle will be automatically ground and the machine automaticallystopped at the completion of the grinding cycle for enabling theoperator to remove the finished article and insert another articlepreparatory to the next grinding cycle.

In Fig. 22 the numeral 400 denotes generally a pump for circulating afluid from a sump or reservoir 402 through a pressure line 260, thenumeral 404 denoting a drain line under atmospheric pressure and thenumeral 406 an exhaust line in which the pressure is somewhat aboveatmospheric pressure.

Fluid will be introduced at a predetermined pressure into high pressureline 2110, and through line 410 to a spring actuated relief valve 412,the fluid being discharged from the valve through lines 414 and 416,wherein line 416 is in open communication with exhaust line 406, andwherein line 414 is in communication with intake 418 of a double-acting,two-way valve 420 which is normally maintained in the positionillustrated in the drawing by means of spring 422 whereby fluid enteringport 418 will be discharged via line 424- into exhaust line 416. In thismanner the net pressure of fluid in line 200 will be considerablyreduced, thereby lessening the energy required to operate pump 406i andprecluding undue heating of the pressure media.

A double-acting, four-way reversing valve 426 is normally conditioned bymeans of spring 428 to connect line 430 in open communication with line432 to end 434 of the cylinder 166 which, through piston rod 164,actuates feed arm 142 about shaft 148 for normally disposing the saidfeed arm in a fully elevated position.

A solenoid indicated generally by the numeral 436 is adapted to reversevalve 426 whereby fluid under pressure from line 430 will be introducedinto line 438 which is in open communication with end 440 of cylinder166. Line 442 is in open communication with line 438 for transmittingthe pressure within line 438 and end 440 of cylinder 166 to a pressureswitch 444.

Exhaust line 406 is connected to the discharge port 446 of valve 426 vialine 443. Drain line 404 is suitably connected through line 450 to thatside of valve 426 with which spring 428 is associated for returning anyleakage which might occur in the valve back to sump or container 402.

End 452 of cylinder 250 is normally connected in open communication withpressure line 200 through line 454 to intake 456 of a double actingvalve 458, line 460, rate valve 462, check valve 464 and lines 466 and468. A second rate valve 470 is connected between lines 460 and 468 bylines 472 and 474, it being noted that a double acting valve 476controls the flow of fluid through rate valve 470. A spring 478-normally maintains valve 476 in closed condition, said valve beingopened incident to energization of solenoid 480 for establishing a flowof fluid through the last mentioned rate valve.

Spring 459 normally maintains valve 458 whereby line 460 is in opencommunication with line 454. A solenoid 461 is provided for actuatingthis valve for selectively connecting line 482 in open communicationwith line 454.

The spring loaded ends or other portions of the housing of each ofvalves 45% and 476 are connected to drain line 404 by lines 484 and 486,respectively. Each of the rate valves 462 and 470 are likewise connectedvia lines 488 and 490 to the drain line 404.

From the foregoing it will be noted that end 452 of cylinder 250 will benormally subjected to fluid pressure for disposing feed wedge 220 in afully advanced position for elevating post 210.

Fluid from line 200' is likewise supplied to doubleacting valve 120 vialine 492 for distribution through lines 494 and 496 to one or the otherof cylinders 94 and 96, the pistons and 92' of which, note Fig. 18,engage opposite ends of power rack 58.

The intake 498 of pilot valve 116' is connected by line 500 to pressureline 200, and when this valve is in the position illustrated in Fig. 22,the fluid of line 500 will be introduced into cylinder 502 through line503 for shifting valve 120 for introducing fluid into cylinder 96, itbeing understood that the pilot valve is actuated by dogs 108 and 110contacting levers 112 and 114, see Fig. 18. When lever 114 has beenshifted to the left, fluid from line 500 will be introduced through line504 to cylinder 506 for introducing fluid from line 492 into cylinder 94via line 494.

Line 507 connects outlet port 568 of valve in open communication withdouble-acting valve 510 which is normally closed by spring 512 forthereby precluding a flow of fluid through line 492 whereby pistons 90-and 92 will remain stationary. A solenoid 514 is provided for actuatingvalve 510 to an open position connecting line 507 with line 516, throughan adjustable rate valve 513 to exhaust line 406 via line 520. The ratevalve is connected to drain line 404 by line 522.

A solenoid 524 is provided to actuate valve 428 for blocking the flow offluid therethrough to line 416, thereby increasing the pressure of fluidin line 294).

A suitable filter 530 is provided in exhaust line 4% and a safety valve532 is placed in parallelism with the filter for precluding damagethereto incident to clogging thereof.

After the pump 400 has been operated for providing fluid under pressurein line 260, and after an article has been mounted on the upper cradle,the operator may then initiate a cycle by which a flow of coolant isestablished, motor 146 started for driving belt and solenoids 436, 480and 524 energized. Energization of solenoid 436 will actuate valve 426for applying fluid under high pressure to end 440 of cylinder 166 forrapidly lowering feed arm 142 until button 212 engages the free upperend of post 210.

Energization of solenoid 480 will place rate valve 470 in opencommunication between lines 472 and 468.

Energization of solenoid 524 actuates valve. 420 to block the flow offluid therethrough for placing line 200 under high pressure.

A pressure build up will occur in end 440 of cylinder 166 after theinitial rapid lowering motion of feed arm 142 has been checked by post210. This build up in pressure actuates the pressure switch 444 forclosing an electrical circuit to solenoids 461 and 514 for actuatingvalves 458 and 510, respectively, to introduce fluid from line 454 toline 482 and connect line 460 with exhaust 406 via line 411, forretracting the feed wedge 220, thereby lowering post 210; and forsimultaneously placing exhaust line 507 in open communication with line516 for permitting fluid to flow from one or the other of cylinders 94and 96 forreciprocating the power rack 58.

When limit switch 260, see Fig. 15, has been actuated, solenoid 480 isde-energized for actuating valve 476 to interrupt a flow of fluid,through 472 sojthat the exhaust of fluid from end 452 of cylinder 250 isrestricted to line 466, thereby providing a slow feed of the feed wedge220 and a very slow lowering of post 210.

As best illustrated in Fig. 15, a limit switch 351 is mounted whereby itwill be actuated by the free outer end 258 of rod 254 as feed wedge 220reaches the end of its stroke. Switch 351 opens an electric circuit to aso-called tarry timer, not illustrated, which initiates a short dwellafter the post 210 has been fully lowered for thereby permitting thegrinding operation to continue for a moment or two with the conjugateform, endless belt and article being ground'in fixed relationship forthereby enabling so-called spark-out to occur, and to allow anydeflections induced incident to the grinding operation to be relieved.

Upon termination of the cycle of thetarry timer, the electrical circuitto solenoid 436 is interrupted and spring 428 will actuate valve 426whereby fluid will be applied to end 434 of cylinder 166 for therebyshifting arm 142 to its fully elevated position in the case of theconvex machine illustrated in Fig. 11.

At the same time switch 363 is energized so that actuation of overridinglever 1363 by dog 361 secured to and carried by control rack 106 willresult in de-energization of each of solenoids 461, 514 and 524, itbeing noted that .the cradle will thus be stopped in the same relativeposition at the termination of each grinding cycle.

The grinding belt and flow of coolant are likewise stopped concurrentlywith the de-energization of solenoids 461, 514 and 524.

Suitable means are preferably provided for enabling the cradle and itsassociated driving rack to be actuated by hand during those periods oftime when the device is being manipulated incident to set-up. Such meansmay comprise a needle valve 550 disposed between lines 494 and 496,thereby permitting the fluid in each of cylinders 94 and 96 to freelypass from one cylinder to another incident to axial movement of therack.

Concave grinding In those instances wherein it is desirable to grind theconcave surface of an article, we prefer to utilize the deviceillustrated in Figs. 1 through 10. At the outset it may be noted thatthe primary distinction between convex grinding and concave grinding, byour method, amounts to a mere reversal of parts, in the sense that inconvex grinding we propose to mount the conjugate form in a stationaryposition and of then moving the article to be ground about the fixedlymounted form in such a manner that the surface of the form will bedisposed in conjugate coincidence with the surface of the article beingmoved thereabout. When grinding concave surfaces we fixedly mount thearticle to be ground relative to the conjugate form which is movedrelative to the fixedly mounted article for disposing the surface of theform in conjugate coincidence with the surface of the article incidentto movement of the form relative thereto. In both grinding operations anendless belt is caused to pass over and is guided by the conjugate form,the grinding operation being accomplished by reason of eflectingcontacting relationship of the article with the abrasive surface of thebelt as guided by the conjugate form.

With particular reference now to Fig. l, the numeral 166 denotes acylinder one end of which is pivotally secured as at 168 to a bracket169 secured to and projecting downwardly from the housing 31. Piston rod164 is pivotally secured as at 161 to the lower end of lever 159 theupper end of which lever is keyed to shaft 149 for rotation therewith.One end of the feed arm 143 is provided with a clamp 141 which issecurely though releasably anchored to shaft 149 by means of bolts, orthe like, 145. A bearing bracket 151 is suitably secured to a side wallof the housing as by a weld, said bracket rotatably receiving the outerend of shaft 149, note Fig. 2. The numeral 123 denotes a pad to which anarticle to be ground is securely though releasably attached.

The introduction of fluid under pressure into the left end of thecylinder 166 will shift the piston rod 164 to the right for therebyelevating feed arm 143 upwardly about shaft 149.

With particular reference now to Figs. 2 and 8, it will be 'noted thatfree, unrestrained upward movement of feed arm 143 will be resisted bythe upper end of abutment 213 with the free lower end of pin 215.

The numeral 211 denotes a post which is identical with and a substantialduplicate of post 210 as more fully detailed in Fig. 13, it beingfurther understood that axial movement of post 211 is accomplished bythe same or a similar mechanism illustrated in Fig. 13 for controllingthe axial movement of post 210.

Upward axial movement of pin 215 is translated to a parallel, downwardaxial movement of rack or counter shaft 217- the lower end of which mayterminate in a rodlike portion 229 the free end of which may abuttinglyengage the free upper end of post 211.

As clearly illustrated in Fig. 8, pin 215 is integral with a rack 221,the teeth of which engage the teeth of a pinion gear 223 rotatablymounted for movement about shaft 225 the opposite ends of which shaftare supported by and spanningly engage a pair of duplicate side plates227 of housing 233. The teeth of gear 223 are likewise in engagementwith the teeth of rack 217 wherein the axis of racks 221 and 217 are inspaced parallelism whereby movement of one rack in one direction willproduce an equal and opposite movement of the other rack.

- With reference now to Fig. 9, it will be noted that the free lower endof rod 229 is adapted to abuttingly engage the upper surface of anoffset plate 231 secured to and carried by the free upper end of post211. It should, of course, be understood that the free lower end of pin229 could be in axial alignment with post 211, however we haveascertained that by using offset plate 231, as illustrated, an alignmentproblem is effectively solved without in any way impairing theefliciency of the device.

Referring again to Fig. 8, it will be noted that the racks 221, 217,-gear 223 and shaft 225 may be secured to and housed within a bracket 233secured by means of bolts 235 to wall 237 of the frame.

It will be understood that upward movement of feed arm 143 will thus beresisted by the counter-force of post 211 by means of actuation of wedge220 of Fig. 13.

As earlier indicated in concave grinding we propose to move theconjugate form along a predetermined path during the grinding operation.The particular means utilized to accomplish the, desired motion of theconjugate

